The invention relates to a pressure cooker including a container which is intended to hold a cooking produce and which can be closed in a pressure tight manner by a cover that can be set on a rim of the container and locked therewith. The cover includes closing members that can be moved between open positions, in which the cover can be removed from the container, and locking positions, in which the circumference of the cover is pressed against a region of the container rim with a circumferential sealing ring therebetween.
Such a pressure cooker in known, for example from EP-A 0 108 203. In such known arrangement, the cover includes a centered hood and a frame. The frame sits by way of a sealing profile on a container rim that is bent down towards the outside. Locking members in radially inward locking positions thereof reach with an outer flange that is bent inwardly toward the bottom under the container rim. The cross section of the sealing profile is somewhat U-shaped and one sealing lip formed on a bottom end thereof rests against the container rim.
It is desired to impart to pressure cookers the least commercial appearance as possible despite expensive equipment thereof necessary to maintain safety requirements, to guarantee ease of handling when putting on, locking and unlocking the cover on the container, and to meet high safety requirements during use and handling of parts that are as simple as possible. The known pressure cooker cannot meet in a satisfactory manner these different requirements. In particular, a relatively complicated seal is necessary. Also, setting the cover on the container requires considerable dexterity, because, when viewed from the top, the outer diameter of the cover that is defined by the closing members does not correspond to the cover opening that is intended to accommodate the container rim. Further, the appearance of the cover is determined automatically by the closing members, because they have to envelope outwardly the hood, the frame and the container rim.
A pressure vessel for food to be used in a microwave oven is known from EP-A 0 112 295. The cover of such pressure vessel can be set pressure-tight on the container. In so doing, a cover body lies on an inner shoulder of a container wall. A gap between the outer circumference of the cover and the inner surface of the container wall is covered by a sealing ring that is arranged in an inner circumferential groove of the container wall at a distance above the inner shoulder that can be removed from such groove by means of a pull strap. To close the vessel the cover body is set on the inner shoulder of the container wall. Then the sealing ring, separated by hand, is inserted into the inner circumferential groove. While the vessel is being used for cooking, the entire inner pressure is absorbed by the sealing ring, whose clear inner diameter is somewhat less than the outer diameter of the cover body. Thus, necessary safety requirements cannot be met if operation is to be at higher pressure as in a pressure cooker, especially if additional measures to relieve the pressure are not taken, which, however, also can fail. When such known vessel is closed and opened, the cover body and the sealing member must be handled separately in an awkward manner.
A similar cooking vessel is known from CH-A-273 354. Here, too, in order to subsequently close the cover with respect to the container, a sealing ring, which is provided with a strap for removal, has to be inserted into a circumferential groove of the container rim that is accessible from the top.
A pressure cooker known from FR-A 2 531 847 has a cover equipped with a bracket that can be adjusted in axial distance from a cover body. In a locking position, outer ends of the bracket reach under two diametrically opposite catch hooks attached to the container rim. In the locking position the cover body itself rests with an O-ring, disposed in a circumferential groove, against an upper end of the container rim. The locking and opening of such a pressure cooker is relatively tedious, since the bracket must be adjusted with a spindle relative to the cover body. In addition, such a pressure cooker does not offer the requisite safety because the bracket is braced only at its two ends, and the catch hooks and/or the bracket can deform when subjected to considerable pressure. There is also the problem that the pressure prevailing in the vessel interior must be detected by the spindle.